Device and method for displaying information, radar apparatus

ABSTRACT

This disclosure provides an information display device, which includes a sensor signal acquirer for acquiring a sensor signal indicating a content detected by a sensor, a signal processor for performing first signal processing and second signal processing different from the first signal processing, on the sensor signal, and a display unit for displaying on a screen image, first information of the sensor signal after the first signal processing, and partial information of second information of the sensor signal after the second signal processing in a different display mode from the first information, the partial information being different from the first information.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The application claims priority under 35 U.S.C. §119 to Japanese PatentApplication No. 2011-207411, which was filed on Sep. 22, 2011 the entiredisclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to an information display device fordisplaying information detected by a sensor.

BACKGROUND OF THE INVENTION

Generally, antennas provided to radar apparatuses receive not only anecho (reflection wave) from a target object or a land, but also an echofrom a wave surface (sea surface clutter) and an echo from rain or snow(rain-and-snow clutter). Therefore, in order to suppress (remove) suchan unnecessary echo, conventionally, processing of subtracting apredetermined value from a signal level of the echo (gain adjustmentprocessing) has been performed.

Hereinafter, the gain adjustment processing for suppressing the seasurface clutter is exemplary explained with reference to FIGS. 8A to 9C.FIGS. 8A to 8C are charts showing how the sea surface clutter issuppressed by appropriate gain adjustment processing. FIGS. 9A to 9C areviews showing display screens when the gain adjustment processing isperformed at different levels, respectively.

FIG. 8A is a chart showing echo signals (including the sea surfaceclutter) before the gain adjustment processing. As shown in FIG. 8A, thesea surface clutter generally has a property in which the signal levelthereof is high at a position close to a radar antenna, but it lowersrapidly as it is further distant from the radar antenna. Inconsideration of this property, there has been a radar apparatus setwith a curve for lowering a value of the signal level to be removed (seasurface clutter removing curve). The signal level is lowered more as thesea surface clutter is further distant from the antenna (see FIG. 8B).By subtracting the value obtained from the sea surface clutter removingcurve an echo signal having a level indicating only a ship can beextracted from the echo signal before the gain adjustment processing(the sea surface clutter can be suppressed) (see FIG. 8C).

Similarly, by further suppressing other unnecessary echoes, such as therain-and-snow clutter, a radar image in which the unnecessary echoes areappropriately suppressed (FIG. 9B) can be created. In this manner,necessary echoes can be displayed to be viewed easier comparing to aradar image created without the gain adjustment processing (FIG. 9A).

JP2011-002425A discloses a radar apparatus having a configuration foreffectively removing the rain-and-snow clutter. Based on an echo signalreceived by the radar apparatus, a section determiner provided to theradar apparatus determines whether a distance range where the echoexists is in “a land/target-object section” or “a rain-and-snow/noisesection.” Further, the radar apparatus suppresses the rain-and-snowclutter within the distance range determined as “the rain-and-snow/noisesection”, by using a value determined according to the echo signalwithin the distance range.

Note that, the radar apparatus disclosed in JP2011-002425A also has theconfiguration of displaying the range determined as “therain-and-snow/noise section” filled in a translucent color.

Meanwhile, it is not easy to set the sea surface clutter removing curvefor the gain adjustment processing. For example, when the value of thesea surface clutter removing curve is excessively high as shown in thechart of FIG. 10A, even the echo signal indicating the ship issuppressed (FIG. 10B). As a result, a radar image in which necessaryinformation is also suppressed is created (FIG. 9C).

Therefore, when the radar image is displayed with hardly anything, anoperator referring to the radar image may be confused whether the echoindicating the ship is suppressed by the signal processing or the shipitself does not exist. In this case, the operator needs to set the levelof the gain adjustment processing to perform the processing again so asto confirm the existence of the ship.

This situation has been a common problem for not only ship radarapparatuses but various kinds of equipments with the possibility ofcontents detected by a sensor being suppressed through performing signalprocessing thereon.

SUMMARY OF THE INVENTION

The present invention is made in view of the above situation, andprovides an information display device for displaying informationobtained through performing predetermined signal processing on contentsdetected by a sensor, in which the information is displayed so that anoperator can grasp whether a detection target is not displayed onlybecause of the predetermined signal processing or it originally does notexist.

According to one aspect of the invention, an information display device,which includes a sensor signal acquirer for acquiring a sensor signalindicating a content detected by a sensor, a signal processor forperforming first signal processing and second signal processingdifferent from the first signal processing, on the sensor signal, and adisplay unit for displaying on a screen image, first information of thesensor signal after the first signal processing, and partial informationof second information of the sensor signal after the second signalprocessing in a different display mode from the first information, thepartial information being different from the first information.

In this manner, the main partial sensor image (first information) andthe supplemental partial sensor image (second information) can bedisplayed simultaneously. Therefore, even if the first information ispartially suppressed excessively by performing the first signalprocessing to remove, for example, noises, a part of the secondinformation can be displayed for the suppressed part of the firstinformation instead. Therefore, for example, when the detection targetis not displayed on the screen image, it can be prevented that anoperator is confused whether the ship is not displayed only because ofthe signal processing or it originally does not exist.

The first information may be displayed with gradation in color, and thesecond information is displayed with no gradation in color.

In this manner, the contents of the first information (e.g., intensityof a measured value) can easily seen and the second information caneasily be grasped from all the information. Especially, by using adisplay mode of not excessively emphasizing the second information(e.g., hatching), the second information can be instinctively graspedthat it is the supplemental information.

A display color of the first information may be different from a displaycolor of the second information.

In this manner, the first and second information can be discriminatedwith such a simple configuration. Especially, by using a display colorthat does not excessively emphasize, for the second information, thesecond information can be instinctively grasped that it is thesupplemental information.

The first signal processing may correspond to the second signalprocessing with additional processing.

In this manner, even if the first information is partially suppressedexcessively by the additional signal processing, a part of the secondinformation can be displayed for the suppressed part of the firstinformation instead. Therefore, for example, high level noisesuppressing processing can be performed while referring to the detectiontarget of the sensor.

The similar kind of signal processing may be used in the first signalprocessing and the second signal processing, and parameters used in thefirst signal processing and the second signal processing may bedifferent from each other.

In this manner, if the signal processor performs the noise suppressingprocessing, by using the different parameters between the first andsecond signal processing, even when a noise is sufficiently suppressedand the first information partially disappears from the screen image,the disappeared information can be displayed as the second information.

The similar kind of the signal processing may be gain adjust processing.

In this manner, even if a signal level of the noise and a signal levelof the detection target are close and the gain adjustment processing isperformed to lower the levels, it can be prevented that the detectiontarget disappears from the screen image.

The similar kind of the signal processing may be scan-to-scancorrelation processing.

In this manner, even when the scan-to-scan correlation processing isperformed to lower the signal level of the detection target in rapidmovement, it can be prevented that the detection target disappears fromthe screen image.

One of the parameters of the first and second signal processing may beadjusted automatically, and the other parameter may be adjusted based ona value set by an operator.

In this manner, the signal processing performed through the operation bythe operator and the signal processing adjusted automatically can besupplemented mutually.

One of the parameters of the first and second signal processing may be avalue obtained by either one of increasing and reducing the otherparameter by a predetermined amount.

In this manner, for example, the detection target can be displayed asthe second information before it disappears from the first informationby adjusting the parameters. Therefore, the parameters can be set againbefore the display target completely disappears from the screen image.

According to another aspect of the invention, a radar apparatus isprovided, which includes the information display device of any of theother aspects, and a radar antenna serving as the sensor.

When the radar apparatus for detecting a movable body is used, becauseit is desired for the operator to surely grasp whether the movable bodyis not displayed on the screen image because of the signal processing orit originally does not exist, the above configuration can particularlyeffectively exert an effect of the invention that the operator can graspthe situation.

According to further another aspect of the invention, a sonar apparatusis provided, which includes the information display device of any of theother aspects, and a sonic wave reception device serving as the sensor.

In this manner, the above effect of the invention can be exerted by thesonar apparatus.

According to still another aspect of the invention, a method ofdisplaying information is provided, which includes acquiring a sensorsignal indicating a content detected by a sensor, performing firstsignal processing and second signal processing different from the firstsignal processing, on the sensor signal, and displaying on a screenimage, first information of the sensor signal after the first signalprocessing, and partial information of second information of the sensorsignal after the second signal processing in a different display modefrom the first information, the partial information being different fromthe first information.

In this manner, the main partial sensor image (first information) andthe supplemental partial sensor image (second information) can bedisplayed simultaneously. Therefore, even if the first information ispartially suppressed excessively by performing the first signalprocessing to remove, for example, noises, a part of the secondinformation can be displayed for the suppressed part of the firstinformation instead. Therefore, for example, when the detection targetis not displayed on the screen image, it can be prevented that anoperator is confused whether the ship is not displayed only because ofthe signal processing or it originally does not exist.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is illustrated by way of example and not by wayof limitation in the figures of the accompanying drawings, in which thelike reference numeral indicate like elements and in which:

FIG. 1 is a block diagram of a radar apparatus according to anembodiment of the present invention;

FIG. 2A is views showing first information and second information,respectively, and FIG. 2B is a view showing a sensor image created fromthe information;

FIG. 3 is a view showing a display example of the sensor image;

FIG. 4A is a chart showing echo signals before gain adjustmentprocessing by a second signal processing module, and FIG. 4B is chartsexplaining the gain adjustment processing performed by the second signalprocessing module in a case of removing a background noise;

FIG. 5A is charts explaining the gain adjustment processing performed bythe second signal processing module in a case of removing the backgroundnoise and a sea surface clutter, and 5B is charts explaining the gainadjustment processing performed by the second signal processing modulein a case of removing the background noise, the sea surface clutter, andthe rain-and-snow clutter;

FIG. 6 is a chart explaining another example of the gain adjustmentprocessing performed by the second signal processing module;

FIGS. 7A to 7F are block diagrams showing examples of processingperformed by a first signal processing module and the second signalprocessing module;

FIGS. 8A to 8C are charts showing how the sea surface clutter issuppressed by appropriate gain adjustment processing;

FIGS. 9A to 9C are views showing display screens when the gainadjustment processing is performed at different levels, respectively;and

FIGS. 10A and 10B are charts showing a case where even an echoindicating a ship is suppressed by excessive gain adjustment processing.

DETAILED DESCRIPTION

Next, an embodiment of the present invention is described with referenceto the appended drawings. FIG. 1 is a block diagram of a radar apparatus1 according to this embodiment. FIG. 2A is views showing firstinformation and second information, respectively, and FIG. 2B is a viewshowing a sensor image created from the information. FIG. 3 is a viewshowing a display example of the sensor image.

The radar apparatus 1 is a ship radar to be provided on a ship(hereinafter, may be referred to as “the ship concerned” or may besimply referred to as “the ship”), such as a fishing boat, and isgenerally used to detect a target object, such as another ship. As shownin FIG. 1, the radar apparatus 1 includes an antenna unit 10 and a radarinstruction device 20 (image display device).

The antenna unit 10 is attached to a predetermined position in the ship,and has a radar antenna 11 (sensor) and a transceiver 12.

The radar antenna 11 transmits a pulse-shaped electric wave having astrong directivity and receives an echo (reflection wave) from thetarget object. Further, the radar antenna 11 measures a time lengthbetween the transmission of the pulse-shaped electric wave and thereception of its echo, and thereby, a distance from the ship to thetarget object can be grasped. Moreover, the radar antenna 11 can revolvehorizontally over 360°, and repeatedly transmit and receive the electricwave while horizontally changing a transmission direction of theelectric wave (while changing a facing direction of the radar antenna11). With the above configuration, the detection of the target objectcan be performed horizontally over 360° centering on the ship.Hereinafter, an operation between the transmission of the pulse-shapedelectric wave and the next transmission thereof may be referred to as“the sweep.”

Note that, either one of a CW (continuous wave) radar and a pulsedoppler radar may be used alternative to the pulse radar. Further,alternative to the radar apparatus of this embodiment, a radar apparatushaving a configuration in which the radar antenna does not revolve maybe used. For example, with either one of a radar apparatus having aconfiguration with antenna elements in the entire circumferentialdirection and a radar apparatus for detecting only a particulardirection (e.g., forward), the radar antenna is not required to revolvefor detecting around the ship.

The transceiver 12 samples an echo signal received by the radar antenna11 so as to be digitized, and outputs the digitalized echo signal(sensor signal) to the radar instruction device 20.

The radar instruction device 20 includes a sensor signal acquirer 21, asweep memory 22, a signal processor 23, an image processor 24, a displayunit 25, and a user interface 26.

The sensor signal acquirer 21 is an interface for communicating with theantenna unit 10. The sensor signal acquirer 21 acquires the sensorsignal indicating a detection result from the radar antenna 11 andoutputs it to the sweep memory 22.

The sweep memory 22 is a buffer memory that can store sensor signals forone sweep in real time. The sweep memory 22 is stored with the sensorsignals sampled during one sweep, in a chronological order. Therefore,based on a read address of when the sensor signal is read out from thesweep memory 22, the distance to the target object (source of the echo)corresponding to the sensor signal can be obtained. Further, an azimuthsensor (not illustrated) is attached to the radar antenna 11, and adetection result from the azimuth sensor is also transmitted to thesweep memory 22 via the sensor signal acquirer 21. Therefore, when thesensor signal is read out from the sweep memory 22, a position of thetarget object corresponding to the sensor signal can be obtained.

The signal processor 23 performs predetermined signal processing (firstsignal processing and second signal processing) based on the sensorsignal inputted from the sweep memory 22. The signal processor 23 isconstituted with a first signal processing module 51 and a second signalprocessing module 52. In this embodiment, both the first signalprocessing module 51 and the second signal processing module 52 performgain adjustment processing.

The first signal processing module 51 performs the gain adjustmentprocessing on the echo signal by using a gain adjustment parameteraccording to an operation by an operator, and creates a first radarimage (first information) based on the adjusted echo signal (see theupper view of FIG. 2A). Although the first information is displayed in asingle color in the upper view of FIG. 2A, actually a gradation of thecolor is changed in the display according to an echo signal level. Notethat, any arbitrary color may be used in displaying the firstinformation. The first information created by the first signalprocessing module 51 is outputted to the image processor 24.

The second signal processing module 52 calculates the gain adjustmentparameter based on the sensor signals acquired by the sensor signalacquirer 21 and performs the gain adjustment processing by using thecalculated gain adjustment parameter. Further, the second signalprocessing module 52 creates a second radar image (second information)based on the adjusted echo signal (see the lower view of FIG. 2A).Unlikely to the first information, the gradation of a display color ofthe second information does not change. That is, the second signalprocessing module 52 creates the second information based on whether theecho signal level is higher than a predetermined threshold. Note that,the threshold may be set to change according to the distance from theship to the corresponding target object. The second information createdby the second signal processing module 52 is outputted to the imageprocessor 24. Processing of creating the second information by thesecond signal processing module 52 is described below in detail.

The image processor 24 creates a combined sensor image (hereinafter, maysimply be referred to as “the sensor image”). Here, the image processor24 creates the sensor image by superimposing the first information onthe second information (see FIG. 2B). That is, the image processor 24creates the sensor image by combining the first information and a partof the second information that is different from the first information(the part that does not overlap with the first information). The imageprocessor 24 outputs the thus created sensor image to the display unit25.

The display unit 25 is a liquid crystal display that can display in fullcolor. As shown in FIG. 3, the display unit 25 displays the sensor imageon a display screen.

The user interface 26 includes operation keys and an operation knob. Theoperator operates the user interface 26 to be able to perform variousoperations and instructions to the components such as the radarinstruction device 20. Especially, in this embodiment, the operator canspecify a set value of the gain adjustment processing which is performedby the first signal processing module 51, through operating the userinterface 26. The first signal processing module 51 changes theparameter for the gain adjustment processing based on the set value.

As described above, the display unit 25 can simultaneously display themain radar image (first information) and the supplemental radar image(second information). In this manner, even if the operator operates theuser interface 26 to set a comparatively high gain adjustment parameterand, thereby, the echo indicating, for example, the ship disappears fromthe display screen, the echo (i.e., a potential echo excluded from thefirst information) can be displayed as the second information.Therefore, it can be prevented that the operator overlooks the echo.

Next, the gain adjustment processing performed by the second signalprocessing module 52 so as to determine the existence of the targetobject is explained with reference to FIGS. 4A to 5B.

FIG. 4A is a chart showing the echo signals (sensor signals) before thegain adjustment processing. As shown in FIG. 4A, the echo signalsinclude, in addition to the echo signals from the other ships, the echosignals from a wave surface (sea surface clutter), from rain and/or snow(rain-and-snow clutter), and background noises. Note that, amongcountless number of methods of performing the gain adjustment processingby the second signal processing module 52, in the description below,parameters used in case 1: gain adjustment processing of removing thebackground noises, case 2: gain adjustment processing of removing thesea surface clutter and the background noises, and case 3: gainadjustment processing of removing the sea surface clutter, therain-and-snow clutter, and the background noises are explained,respectively.

FIG. 4B shows a background noise removing straight line for removing thebackground noises. The background noise removing straight line isobtained by averaging the signal levels of the echo signals from far indistance. First, the second signal processing module 52 subtracts avalue obtained from the background noise removing straight line, fromeach of the signal level of the received echo signal. Next, the secondsignal processing module 52 determines that the target object (e.g.,ship) exists in an area where the echo signal level is still left (i.e.,the signal level is above 0) as a result of the subtraction. As above,the second signal processing module 52 determines the existence of thetarget object by removing the background noises in the case of FIG. 4B.

FIG. 5A shows a sea surface clutter removing curve for removing the seasurface clutter in addition to the above background noise removingstraight line. A sea surface clutter generally has a property in whichthe signal level thereof is high at a location close to the radarantenna 11, but it lowers rapidly as it is further distant therefrom.Therefore, the sea surface clutter removing curve is obtained throughforming an area according to the distance from the radar antenna 11 andaveraging the echo signal levels in the area. Among the received echosignals, the second signal processing module 52 subtracts a valueobtained from the sea surface clutter removing curve, from each of thesignal levels of the echo signals in the area where the sea surfaceclutter is dominant, and subtracts the value obtained from thebackground noise removing straight line, from the signal levels of restof the other echo signals. Next , the second signal processing module 52determines that the target object (e.g., ship) exists in an area wherethe echo signal level is still left as a result of the subtractions. Asabove, the second signal processing module 52 determines the existenceof the target object by removing the sea surface clutter and thebackground noises.

FIG. 5B shows a rain-and-snow clutter removing curve for removing therain-and-snow clutter in addition to the above sea surface clutterremoving curve and background noise removing straight line.Rain-and-snow clutter is generally influenced also by weather, on top ofthe distance from the radar antenna 11. Therefore, in the gainadjustment processing of this case, the processing of obtaining the seasurface clutter removing curve is also performed for a location far fromthe radar antenna 11 in addition to the location close thereto. Thus,the curves and the straight line with which the sea surface clutter, therain-and-snow clutter, and the background noises can be removed can beformed. The second signal processing module 52 subtracts the valuesobtained from the above curves and straight line from the signal levelsof the echo signals respectively and, for an area where the signal levelis still left, the second processing module 52 determines that thetarget object (i.e., ship) exits. In this manner, the second signalprocessing module 52 determines the existence of the target object byremoving the sea surface clutter, the rain-and-snow clutter, and thebackground noises.

By obtaining the gain adjustment parameter based on the received echosignals and subtracting one or more of the values of the parameter fromthe signal levels of the echo signals respectively, the second signalprocessing module 52 derives a satisfactory valid result about theexistence of the target object. Therefore, the display screen of thedisplay unit 25 can keep displaying the valid result as the supplementalradar image.

Note that, alternative to the above configuration, the gain adjustmentparameter of the second signal processing module 52 may be set throughthe operation by the operator, and the gain adjustment parameter of thefirst signal processing module 51 may be calculated automatically. Withthis configuration, the main radar image (first information) is createdby using the automatically calculated gain adjustment parameter;therefore, this is suitable for a case where the gain adjustmentparameter can be calculated accurately.

A further alternative configuration includes, as shown in FIG. 6,setting the gain adjustment parameter of the second signal processingmodule 52 to a value smaller than the gain adjustment parameter of thefirst signal processing module 51 by a predetermined value. With thisconfiguration, when an echo is excluded from the first information anddisappears from the display screen, the echo is displayed as the secondinformation instead. Therefore, for example, the gain adjustmentparameter of the first signal processing module 51 may be readjustedbefore the echo disappears from the display screen, so that the echoremains on the display screen.

Thus, the method of setting the gain adjustment parameters of the firstand second signal processing modules 51 and 52 is arbitrary as long asthe gain adjustment parameter differs therebetween.

Further, in the above configuration, as shown in FIGS. 7A and 7B, bothof the first and second signal processing modules 51 and 52 perform thegain adjustment processing; however, as shown in FIGS. 7C and 7D,scan-to-scan correlation processing may be performed alternative (or inaddition) to the gain adjustment processing.

The scan-to-scan correlation processing is for correlating a latest echosignal with a previous echo signal so as to suppress a signal of which asignal level randomly varies in term of time (signal having a highcorrelativity with the previous signal) while remaining a signaldetected stably in term of time (signal having a low correlativity withthe previous signal). For example, echo signals indicating the othership, a buoy, and a land are generally detected stably in term of time,and on the other hand, echo signals based on the sea surface cluttergenerally has a signal level that randomly varies in term of time.Therefore, by performing the scan-to-scan correlation processing on theecho signals, only the signals based on the sea surface clutter aresuppressed. However, for example, if the other ship is in rapidmovement, the echo from the other ship is detected at a differentlocation in every scan, and the signal level of the echo appears to beunstable. As a result, the echo from the rapidly moving target objectmay be suppressed.

Note that, by raising the parameter to be used in the scan-to-scancorrelation processing, the signal of which the signal level randomlyvaries in term of time can correspondingly be suppressed more. In theconfiguration shown in FIGS. 7C and 7D, the parameter to be used in thescan-to-scan correlation processing may be differed between the firstand second signal processing modules 51 and 52. For example, theparameter to be used in the scan-to-scan correlation processingperformed by the second signal processing module 52 is lowered than thatfor the first signal processing module 51 by a predetermined amount sothat the echo closest to the lowered parameter is displayedpreferentially, and thereby, when the target object in rapid movement isexcluded from the first information and disappears from the displayscreen, the target object is displayed as the second informationinstead. Therefore, for example, the parameter may be readjusted beforethe echo disappears from the display screen.

Further, the signal processing performed by the first and second signalprocessing modules 51 and 52 may not be the similar kind. For example,as shown in FIGS. 7E and 7F, the first signal processing module 51 mayperform the gain adjustment processing and the scan-to-scan correlationprocessing, and the second signal processing module 52 may perform onlythe gain adjustment processing. In other words, the processing performedby the first signal processing module 51 may be expressed as theprocessing performed by the second signal processing module 52 with theadditional processing.

As above, the first signal processing performed by the first signalprocessing module 51 and the second signal processing performed by thesecond signal processing module 52 may be arbitrary as long as at leastone of the kind and parameter of the signal processing is differenttherebetween.

As explained above, the radar instruction device 20 includes the sensorsignal acquirer 21, the signal processor 23, and the display unit 25.The sensor signal processor 21 acquires the sensor signals indicatingthe contents detected by the radar antenna 11. The signal processor 23performs the first signal processing by the first signal processingmodule 51 and the second signal processing by the second signalprocessing module 52 on the sensor signals acquired by the sensor signalacquirer. The display unit 25 displays the first information after thefirst signal processing on the display screen in a display mode, anddisplays the part of the second information after the second signalprocessing that is different from the first information on the displayscreen in a display mode different from the first information (in thisembodiment, in a different display color).

In this manner, the main radar image (first information) and thesupplemental radar image (second information) can be displayedsimultaneously. Therefore, even if echoes in the first information arepartially not displayed because of the gain adjustment processing,echoes in the second information corresponding to the part of the firstinformation can be displayed instead. Therefore, for example, when thetarget object (i.e., the ship) is not displayed on the display screen,it can be prevented that the operator is confused whether the ship isnot displayed only because of the signal processing or originally doesnot exist.

As above, the suitable embodiment of the present invention is explained.The above configuration may be modified as follows, for example.

The first and second information may be displayed in any arbitrarydisplay mode as long as the display mode of displaying the informationon the display unit 25 is different therebetween. For example, thedisplay mode for the first information may be changed in saturation orbrightness of color according to the signal level, and the secondinformation may be displayed in a translucent or hatched manner. Notethat, because the first and second information are obtained through thesignal processing by the signal processor 23, the mode of displayingimages thereof are not limited to the above embodiment.

The method of creating the sensor image by the image processor 24 isarbitrary as long as the first information is displayed as the mainimage and the part other than the first information are supplemented bythe second information.

The present invention may be applied to other radar apparatusesinstalled in other kinds of movable bodies (e.g., aircrafts), and radarapparatuses installed in fixed bodies (e.g., a lighthouse) for observinga location of a movable body, in addition to the ship radar apparatus.Further, the present invention may be applied to sonar apparatuses fordetecting positions of fish and sea bottom by using a sonic wavetransceiving device for transceiving ultrasonic waves, other than theradar apparatus. Moreover, the present invention may be applied to alight measuring device (e.g., spectrometer) for measuring an intensityof each wavelength of light. Thus, the present invention may be appliedto various kinds of equipments for performing signal processing oncontents detected by a sensor.

In the foregoing specification, specific embodiments of the presentinvention have been described. However, one of ordinary skill in thetechnique appreciates that various modifications and changes can beperformed without departing from the scope of the present invention asset forth in the claims below. Accordingly, the specification andfigures are to be regarded in an illustrative rather than a restrictivesense, and all such modifications are intended to be included within thescope of present invention. The benefits, advantages, solutions toproblems, and any element(s) that may cause any benefit, advantage, orsolution to occur or become more pronounced are not to be construed as acritical, required, or essential features or elements of any or all theclaims. The invention is defined solely by the appended claims includingany amendments made during the pendency of this application and allequivalents of those claims as issued.

What is claimed is:
 1. An information display device, comprising: asensor signal acquirer for acquiring a sensor signal detected by asensor; a signal processor for performing first signal processing andsecond signal processing different from the first signal processing, onthe sensor signal; and a display unit for displaying on a screen image,first information of the sensor signal after the first signalprocessing, and second information of the sensor signal after the secondsignal processing in a different display mode from the firstinformation.
 2. The information display device of claim 1, wherein thesecond information which is displayed is partial information of thesecond information being different from the first information.
 3. Theinformation display device of claim 1, wherein the first information isdisplayed with gradation in color, and the second information isdisplayed with no gradation in color.
 4. The information display deviceof claim 1, wherein a display color of the first information isdifferent from a display color of the second information.
 5. Theinformation display device of claim 1, wherein the first signalprocessing corresponds to the second signal processing with additionalprocessing.
 6. The information display device of claim 1, wherein thesimilar kind of signal processing is used in the first signal processingand the second signal processing, and parameters used in the firstsignal processing and the second signal processing are different fromeach other.
 7. The information display device of claim 6, wherein thesimilar kind of the signal processing is gain adjust processing.
 8. Theinformation display device of claim 6, wherein the similar kind of thesignal processing is scan-to-scan correlation processing.
 9. Theinformation display device of claim 6, wherein one of the parameters ofthe first and second signal processing is adjusted automatically, andthe other parameter is adjusted based on a value set by an operator. 10.The information display device of claim 6, wherein one of the parametersof the first and second signal processing is a value obtained by eitherone of increasing and reducing the other parameter by a predeterminedamount.
 11. A radar apparatus, comprising: a radar antenna serving asthe sensor; a sensor signal acquirer for acquiring a sensor signaldetected by the sensor; a signal processor for performing first signalprocessing and second signal processing different from the first signalprocessing, on the sensor signal; and a display unit for displaying on ascreen image, first information of the sensor signal after the firstsignal processing, and second information of the sensor signal after thesecond signal processing in a different display mode from the firstinformation.
 12. A method of displaying information, comprising:acquiring a sensor signal detected by a sensor; performing first signalprocessing and second signal processing different from the first signalprocessing, on the sensor signal; and displaying on a screen image,first information of the sensor signal after the first signalprocessing, and second information of the sensor signal after the secondsignal processing in a different display mode from the firstinformation.
 13. The method of claim 12, wherein the second informationwhich is displayed is partial information of the second informationbeing different from the first information.
 14. The method of claim 12,wherein the first information is displayed with gradation in color, andthe second information is displayed with no gradation in color.
 15. Themethod of claim 12, wherein a display color of the first information isdifferent from a display color of the second information.
 16. The methodof claim 12, wherein the similar kind of signal processing is used inthe first signal processing and the second signal processing, andparameters used in the first signal processing and the second signalprocessing are different from each other.
 17. The method of claim 16,wherein the similar kind of the signal processing is gain adjustprocessing.
 18. The method of claim 16, wherein the similar kind of thesignal processing is scan-to-scan correlation processing.
 19. The methodof claim 16, wherein one of the parameters of the first and secondsignal processing is adjusted automatically, and the other parameter isadjusted based on a value set by an operator.
 20. The method of claim16, wherein one of the parameters of the first and second signalprocessing is a value obtained by either one of increasing and reducingthe other parameter by a predetermined amount.